UC expert forecasts microbial food-safety regs

FIVE POINTS, Calif. — Even though California’s fresh produce industries have a good record in voluntary compliance, federal regulations for microbial food-safety are on their way, says a University of California, Davis postharvest specialist.

Speaking to a group of vegetable growers and PCAs here recently, Trevor Suslow said the regulatory climate has been shaped by national consumer concerns after well-publicized outbreaks of Salmonella, E. coli O157:H7, and other microorganisms.

Suslow said he is "trying to build awareness of coming mandatory GAPs," or good agricultural practices, for microbial food-safety in fresh-market fruits and vegetables, just like those now required for chemical or physical safety.

GAPs, he explained, are becoming a common marketing tool expected by food-safety conscious buyers, and "there’s an expectation for record keeping that was not common 10 years ago."

Many growers and shippers of fresh-market fruits and vegetables are already using GAPs as means of promoting label reputations and high standards of quality.

"One of the main reasons for having a program related to GAPs is for your protection, but more importantly they help you pull yourself -- either as an individual, a company, a region, or a commodity -- out of any potential trace-back investigation if a problem should occur."

Noting that contamination of produce is an issue at all points between the field and the consumer, he said that whenever questions surface, the first suspicion, rightly or wrongly, is that the produce became infected on the farm and not in the back room of a grocery store or restaurant.

Only a few documented cases point back to improper practices in the field, but they were enough to stir public reaction.

According to officials of the GAPs Program at Cornell University, one case of E. coli contamination was blamed on improperly handled mesclun lettuce mix that caused illnesses in Illinois and Connecticut. The lettuce was grown near a cattle operation and a free-range chicken farm, a situation in violation of sound practices.

Records vital

Record keeping for various GAPs is vital, Suslow said, since authorities hold the attitude that "if something was not written down, it didn’t happen."

Compliance can be far-reaching and quite expensive, yet Suslow said it could be an evolving process starting with some basic steps to avoid obvious "no-brainer" sources of contamination.

Some examples of things to avoid: manure piles adjacent to vegetable fields, failure to protect packing facilities from rodents, birds and other pests, use of contaminated irrigation water, and improper worker facilities and hygiene.

He said the U.S. Food and Drug Administration, the agency charged with purity of fresh fruit and vegetables, "is well on its way to requiring commodity-specific GAPs programs, moving beyond general guidelines."

Meanwhile, some California produce growers have become proactive on the subject. One example is the cantaloupe industry, which produces more than a million tons of melons, about 60 percent of the U.S. output, each year. Cantaloupes were associated with Salmonella outbreaks in recent years. Although investigations traced the origin of the infections to locations other than California, the commodity is, nevertheless, at the top of an FDA high-risk list.

The California Cantaloupe Advisory Board, in response to mounting food-safety concerns, published a booklet detailing ways to minimize risk of food borne illness associated with production and handling of cantaloupes.

Booklet as guide

The publication, written by Suslow, describes best management practices, the organisms involved, physiology of the fruit, and the importance of proper temperature and handling.

"The clear message from university research," it reads, "is that once a cantaloupe has been contaminated, removing or killing the pathogen is not an easy task. In order to protect and maintain California’s strong reputation for high-quality melons that are also safe to consume, a comprehensive and standardized food safety program is a necessary goal for the cantaloupe industry to continue to evolve and implement."

Other commodities, including fresh-market tomatoes, lettuce, green onions, and almonds, that have had recurring problems with microbial outbreaks are also under scrutiny by FDA.

Monitoring of tomatoes, Suslow said, was begun after research demonstrated how readily harmful bacteria can invade the fruit.

FDA surveys of produce terminal markets showed that among commodities having spoilage, tomatoes represented a high percentage. And, he said, they found "a disproportionate potential for Salmonella to be associated with tomatoes."

The findings also say that if tomatoes are contaminated with sufficient doses of Salmonella, the infection persists and multiplies as the fruit matures.

After initial exposure of whole fruit to harmful organisms, improper temperatures of tomatoes being sliced or diced for consumption can cause an infection to spread further.

"Even though we consider tomatoes a very acidic fruit, once you cut through the tissue, the pH becomes much more permissive to pathogens," he said.

State low risk

Results from many assays in the laboratory and in the field show that, while the microbial threats exist, California has a relatively low risk of exposure, largely because of its environment of biological buffers and its general growing patterns.

"No matter how many samples you take, you can never guarantee that contamination isn’t out there. But fortunately it is not easy to find here, which is certainly not the case in many other states," Suslow said.

A hypothetical scenario for tomatoes exposed in a series of bad practices, might spell disaster, he said. If a given piece of ground was grazed off in the fall, a fresh-market tomato crop was planted in the spring, the crop was harvested and shipped without a chlorine or ozone wash, and the fruit was then diced for use and not kept at the correct temperature, the risk of contamination would be compounded.

"We have no, or only limited, data on which to base any recommendations for crops, timing, or precise separation between crops and animals, at this time. But we know these pathogens have an extraordinary capacity to survive more than we would have thought before," Suslow said.

Another problem of microbial food-safety is the ability of the pathogens to overcome controls used to combat them. GAP program researchers continue to work on learning how these adaptations occur.

To assist in developing GAP programs in the field and in packinghouses, Suslow and other UC, Davis experts, collaborating with counterparts across the nation, have compiled an array of recommendations, guides and other resources, written and on videos, in English and Spanish versions. They are available through the Web site at http://ucgaps.ucdavis.edu/.